DESCRIPTION: With the recent isolation and identification of osteoclast progenitors and the isolation and purification of osteoclast colony stimulating factor new and exciting avenues of research can now be approached. The development of chemically defined osteoclast hematopoietic reagents would be of inestimable importance for gaining specific information concerning phenomena such as the proliferation of osteoclasts and the role which these cells play in the process of hematopoiesis, bone formation, and bone resorption. The goal of this research is to develop an osteoclast/hematopoieticre agents that will support in vitro osteoclasts colony formation. Culture of osteoclast requires the presence of ill-defined components. The research herein will be to develop osteoclast/hematopoietic reagents and the technology to avoid the use of serum or any other ill-defined component. This reagent will fill the critical void to provide investigators who are working in this exciting area. They have preliminary data indicating that osteoclast/hematopoietic reagents in combination with purified osteoclast colony stimulating factors supported osteoclast colony formation. However, the reagent formulation needs to be further developed since it did not support colony formation equivalent to serum containing reagents. This proposal will develop osteoclasts/hematopoietic kits and reagent medium for osteoclast proliferation that does not require the presence of serum. These reagents will be valuable in assessing the growth parameters of osteoclast in both normal and diseased states. It also will be of value in assessing the cytokines involved in these processes.